It's harder to create movement in water than in air, because water molecules are closer together than air molecules. To show the difference in resistance, physicist Andreas Wahl puts himself in front of a weapon submerged in water and fires it - on himself.

The Ferguson Police Department is testing out a new device which they think might help prevent unnecessary shooting deaths.

“The Alternative” was invented by a retired police officer and is produced by a California-based company called Alternative Ballistics. It’s an orange accessory that sits on the end of a gun and basically slows down the bullet so it is less likely to kill someone (although it has never actually been used on a human).

The company claims it only takes a few seconds to attach the device to the gun, and it doesn’t obstruct the view of the target through the sight.

Here’s a description of how it works according to Alternative Ballistics:

Once the weapon is fired; the bullet embeds itself inside the projectile with no chance of escaping, simultaneously transferring the bullet’s energy, propelling it directly at the target. Once the bullet is fired from the gun into the projectile they permanently become one unit. The docking unit will automatically eject from the weapon and the firearm returns to its normal function before it cycles in a new round.